|Publication number||US6867533 B1|
|Application number||US 09/696,527|
|Publication date||Mar 15, 2005|
|Filing date||Oct 23, 2000|
|Priority date||Oct 22, 1999|
|Also published as||WO2001031714A1, WO2001031716A1|
|Publication number||09696527, 696527, US 6867533 B1, US 6867533B1, US-B1-6867533, US6867533 B1, US6867533B1|
|Inventors||Ji Su, Joycelyn S. Harrison|
|Original Assignee||The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (15), Non-Patent Citations (12), Referenced by (18), Classifications (37), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Pursuant to 35 U.S.C. §119, the benefit of priority from provisional application 60/161,113, with a filing date of Oct. 22, 1999, is claimed for this non-provisional application.
This application is related to co-pending commonly owned patent application Ser. No. 09/696,528, filed Oct. 23, 2000, entitled “Electrostrictive Graft Elastomers.”
The invention described herein was made by an employee of the United States Government and a National Research Council Research Associate and may be used by or for the Government for governmental purposes without the payment of any royalties thereon or therefor.
1. Field of the Invention
The present invention is generally related to tension control of membranes using an electroactive actuator having at least predominantly single axis displacement.
2. Description of the Related Art
Membrane inflatable and deployable space structures are widely employed by the government and commercially as reflectors, antennas, solar arrays, satellites, solar sails, etc. Although these membrane inflatable and deployabe structures are widely used, many challenges exist which limit their performance for high precision applications. Factors affecting precision include surface smoothness, deviation from desired surface profile, surface deformations due to thermal fluctuations, and accurate membrane positioning. Actuation devices are used for many applications, including the shaping, tuning, positioning, controlling and deforming of membrane structures. To operate most effectively in the aforementioned applications, actuation devices require sufficient force and strain, and often need to produce complex motions.
Conventional piezoelectric ceramic, polymer, and composite actuators (including piezoelectric, electrostrictive, and electrostatic) lack the combination of sufficient strain and force to most effectively perform the aforementioned functions. Previous concepts for shaping and tuning membrane structures have primarily involved the use of piezoelectric ceramic materials. These ceramic piezoelectrics have the major problems of large mass, high density, low strain and high brittleness. Generally, piezoceramics also need additional mechanical devices to achieve a shaping, tuning, positioning, controlling or deforming function. In contrast to electroceramics, electroactive polymers are emerging as new actuation materials due to their enhanced strain capabilities.
Tension control of membranes, using electrostrictive polymer actuators exhibiting at least predominantly single axis displacement and having sufficient force and strain, to smooth local surface wrinkles which may result from thermal distortions and other sources is desirable and currently lacking in the related art.
Accordingly, an object of the present invention is to provide an electroactive tension control device.
Another object is to provide an electroactive tension control device wherein the electroactive components have small mass, low density, high strain and low brittleness.
Another object is to provide an electroactively controlled inflatable membrane.
Another object is to provide an electroactive tension control device using electrostrictive polymer actuators.
Another object is to provide an electrostrictive polymer actuator exhibiting displacement along a longitudinal axis when electrically activated.
Additional objects and advantages of the present invention are apparent from the drawings and specification that follow.
In accordance with the present invention, an electrostrictive polmer actuator comprises an electrostrictive polymer with a tailorable Poisson's ratio. The electrostrictive polymer is electroded on its upper and lower surfaces and bonded to an upper material layer. The assembly is rolled tightly and capped at its ends. In a membrane structure having a membrane, a supporting frame and a plurality of threads connecting the membrane to the frame, an actuator can be integrated into one or more of the plurality of threads. The electrostrictive polymer actuator displaces along its longitudinal axis, thereby affecting movement of the membrane surface.
A more complete appreciation of the invention and the many of the attendant advantages thereof will be readily attained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
Referring now to the drawings, and more particularly to
Referring now to
The bonded layers, denoted generally by numeral 340 are tightly rolled, as illustrated in the exploded view of
Obviously, numerous additional modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than is specifically described herein.
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|U.S. Classification||310/328, 310/800|
|International Classification||C08F259/08, H01L41/09, C08F273/00, H01L41/193, C08F283/12, C08F255/10, H01Q15/14, H01L41/053, C08F259/00, C08F265/08, C08F283/00|
|Cooperative Classification||H01L41/053, Y10S310/80, H01Q15/147, C08F255/10, C08F283/12, C08F259/00, C08F265/08, H01L41/193, C08F273/00, C08F283/006, C08F259/08, H01L41/0836|
|European Classification||H01L41/09L, C08F273/00, C08F255/10, H01L41/053, H01L41/09G, H01Q15/14D, C08F265/08, C08F283/12, C08F259/00, H01L41/193, C08F283/00B, C08F259/08|
|Jan 9, 2001||AS||Assignment|
Owner name: NATIONAL AERONAUTICS AND SPACE ADMINISTRATION (NAS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SU, JI;HARRISON, JOYCELYN S.;REEL/FRAME:011495/0131;SIGNING DATES FROM 20001030 TO 20001031
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